Patent Literature 1, for example, describes an EGR (Exhaust Gas Recirculation) control device for accurately controlling an amount of EGR gas by controlling a pressure difference before and behind an EGR control valve. More specifically, in the art, in the EGR control device including a low pressure EGR passage that recirculates exhaust gas to an intake passage from a downstream side of a DPF, and a low pressure EGR control valve provided in the low pressure EGR passage, a throttle valve provided in the intake passage or an exhaust passage is controlled so that a pressure difference in a predetermined range is formed between an upstream side and a downstream side of the low pressure EGR control valve. Thereby, a desired amount of exhaust gas is stably recirculated.
Following is a list of patent literatures which the applicant has noticed as background of the present disclosure.
Patent Literature 1: JP 2008-248729 A
Patent Literature 2: JP 2012-007547 A